docs: def ds_discrete(self, d_min=None, d_max=None, pts=20, limit=1e-9, 
                      method='logarithmic'):
          r'''Create a particle spacing mesh to perform calculations with, 
          according to one of several ways. The allowable meshes are
          'linear', 'logarithmic', a geometric series specified by a Renard 
          number such as 'R10', or the meshes available in one of several sieve 
          standards.
          
          Parameters
          ----------
          d_min : float, optional
              The minimum diameter at which the mesh starts, [m]
          d_max : float, optional
              The maximum diameter at which the mesh ends, [m]
          pts : int, optional
              The number of points to return for the mesh (note this is not 
              respected by sieve meshes), [-]
          limit : float
              If `d_min` or `d_max` is not specified, it will be calculated as the
              `dn` at which this limit or 1-limit exists (this is ignored for 
              Renard numbers), [-]
          method : str, optional
              Either 'linear', 'logarithmic', a Renard number like 'R10' or 'R5' 
              or'R2.5', or one of the sieve standards 'ISO 3310-1 R40/3', 
              'ISO 3310-1 R20', 'ISO 3310-1 R20/3', 'ISO 3310-1', 
              'ISO 3310-1 R10', 'ASTM E11', [-]
      
          Returns
          -------
          ds : list[float]
              The generated mesh diameters, [m]
      
          Notes
          -----
          Note that when specifying a Renard series, only one of `d_min` or `d_max` can
          be respected! Provide only one of those numbers. 
          
          Note that when specifying a sieve standard the number of points is not
          respected!
      
          References
          ----------
          .. [1] ASTM E11 - 17 - Standard Specification for Woven Wire Test Sieve 
             Cloth and Test Sieves.
          .. [2] ISO 3310-1:2016 - Test Sieves -- Technical Requirements and Testing
             -- Part 1: Test Sieves of Metal Wire Cloth.
          '''
          if method[0] not in ('R', 'r'):
              if d_min is None:
                  d_min = self.dn(limit)
              if d_max is None:
                  d_max = self.dn(1.0 - limit)
          return psd_spacing(d_min=d_min, d_max=d_max, pts=pts, method=method)